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.TH SCHED.H 3HEAD "Apr 1, 2008"
.SH NAME
sched.h, sched \- execution scheduling
.SH SYNOPSIS
.LP
.nf
\fB#include <sched.h>\fR
.fi

.SH DESCRIPTION
.sp
.LP
The <\fBsched.h\fR> header defines the \fBsched_param\fR structure, which
contains the scheduling parameters required for implementation of each
supported scheduling policy. This structure contains the following member:
.sp
.in +2
.nf
int    sched_priority    process execution scheduling priority
.fi
.in -2

.sp
.LP
Each process is controlled by an associated scheduling policy and priority.
Associated with each policy is a priority range.  Each policy definition
specifies the minimum priority range for that policy. The priority ranges for
each policy may overlap the priority ranges of other policies.
.sp
.LP
The scheduling policies are indicated by the values of the following symbolic
constants:
.sp
.ne 2
.na
\fB\fBSCHED_OTHER\fR\fR
.ad
.RS 15n
Processes are scheduled according to the traditional Time-Sharing Class (TS)
policy as described in \fBpriocntl\fR(2).
.RE

.sp
.ne 2
.na
\fB\fBSCHED_FIFO\fR\fR
.ad
.RS 15n
Processes are scheduled in the Real-Time (RT) scheduling class, according to
the First-In-First-Out  (FIFO) policy. Processes scheduled to this policy, if
not preempted by a higher priority or interrupted by a signal, will proceed
until completion.
.RE

.sp
.ne 2
.na
\fB\fBSCHED_RR\fR\fR
.ad
.RS 15n
Processes are scheduled in the Real-Time (RT) scheduling class, according to
the Round-Robin (RR) policy. Processes scheduled to this policy, if not
preempted by a higher priority or interrupted by a signal, will execute for a
time period, returned by \fBsched_rr_get_interval\fR(3C) or by the system.
.RE

.sp
.ne 2
.na
\fB\fBSCHED_IA\fR\fR
.ad
.RS 15n
Processes are scheduled according to the Inter-Active Class (IA) policy as
described in \fBpriocntl\fR(2).
.RE

.sp
.ne 2
.na
\fB\fBSCHED_FSS\fR\fR
.ad
.RS 15n
Processes are scheduled according to the Fair-Share Class (FSS) policy as
described in \fBpriocntl\fR(2).
.RE

.sp
.ne 2
.na
\fB\fBSCHED_FX\fR\fR
.ad
.RS 15n
Processes are scheduled according to the Fixed-Priority Class (FX) policy as
described in \fBpriocntl\fR(2).
.RE

.sp
.LP
The values of these constants are distinct.
.sp
.LP
Inclusion of the \fB<sched.h>\fR header will make visible symbols defined in
the header \fB<time.h>\fR.
.SH SEE ALSO
.sp
.LP
.BR priocntl (2),
.BR sched_get_priority_max (3C),
.BR sched_get_priority_min (3C),
.BR sched_rr_get_interval (3C),
.BR time.h (3HEAD)
